Abstract

Motivated by the need for highly efficient far-IR Fabry–Perot étalons for airborne and space astronomy, we have developed a high-yield photolithographic technique for producing low-loss metal-mesh reflectors. We describe the production technique and report on the mesh flatness and uniformity. Optical measurements of meshes produced by this technique show that absorptivity of less than 1% with reflectivity of more than 98% was achieved at the longest wavelengths measured, which proved them to be significantly more efficient than commercially available meshes. This process can achieve wire widths that are less than the mesh thicknesses (typically 3 μm), which extends their applicability to wavelengths as short as ~20 μm without sacrificing mechanical strength for airborne and space-flight applications.

© 1994 Optical Society of America

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References

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  1. J. M. Vaughn, The Fabry–Perot Interferometer (Hilger, Philadelphia, Pa., 1989), Chap. 10, pp. 405–422.
  2. B. Carli, “Reflectivity of metallic films in the infrared,” J. Opt. Soc. Am. 67, 908–910 (1977).
    [CrossRef]
  3. J. P. Casey, E. A. Lewis, “Interferometer action of a parallel pair of wire gratings,” J. Opt. Soc. Am. 42, 971–977 (1952).
    [CrossRef]
  4. K. Sakai, L. Genzel, “Far infrared metal mesh filters and Fabry–Perot interferometry,” Rev. Infrared Millimeter Waves 1, 155–247 (1983).
    [CrossRef]
  5. T. De Graauw, “The ISO short wavelength spectrometer,” in Infrared Astronomy with ISO, Proceedings of the Les Houches Summer School, T. Encrenas, M. F. Kessler, eds. (Nova Science, New York, 1992), pp. 125–138.
  6. P. E. Clegg, “The long wavelength spectrometer in ISO,” in Infrared Astronomy with ISO, Proceedings of the Les Houches Summer School, T. Encrenas, M. F. Kessler, eds., (Nova Science, New York, 1992), pp. 107–122.
  7. M. A. Greenhouse, H. A. Smith, J. Fischer, I. Furniss, B. Swinyard, R. Emery, “Infrared performance characteristics of low-absorption, high-reflectivity metal mesh reflectors,” to be submitted to Appl. Opt.
  8. C. J. Taylor, H. A. Smith, J. Fischer, “Superior freestanding meshes for use as infrared Fabry–Perot elements made with a new photolithographic technique,” Rev. Sci. Instrum. 59, 1094–1097 (1988).
    [CrossRef]
  9. W. Kern, D. A. Puotinen, “Cleaning solutions based on hydrogen peroxide for use in silicon semiconductor technology,” RCA Rev. 31, 187–206 (1970).
  10. H. Smith, F. Bachner, N. Efrenov, “A high-yield photolithographic technique for surface wave devices,” J. Electrochem. Soc. 118, 821–825 (1971).
    [CrossRef]
  11. R. A. Morgan, Plasma Etching in Semiconductor Fabrication (Elsevier, New York, 1985), Chap. 2, pp. 40–42.
  12. K. N. Prettyjohns, J. C. Wyant, “Three-dimensional surface metrology using a computer controlled noncontact instrument,” in Optics in Engineering Measurement, W. F. Fagan, ed., Proc. Soc. Photo-Opt. Instrum. Eng. 599, 304–308 (1986).

1988

C. J. Taylor, H. A. Smith, J. Fischer, “Superior freestanding meshes for use as infrared Fabry–Perot elements made with a new photolithographic technique,” Rev. Sci. Instrum. 59, 1094–1097 (1988).
[CrossRef]

1983

K. Sakai, L. Genzel, “Far infrared metal mesh filters and Fabry–Perot interferometry,” Rev. Infrared Millimeter Waves 1, 155–247 (1983).
[CrossRef]

1977

1971

H. Smith, F. Bachner, N. Efrenov, “A high-yield photolithographic technique for surface wave devices,” J. Electrochem. Soc. 118, 821–825 (1971).
[CrossRef]

1970

W. Kern, D. A. Puotinen, “Cleaning solutions based on hydrogen peroxide for use in silicon semiconductor technology,” RCA Rev. 31, 187–206 (1970).

1952

Bachner, F.

H. Smith, F. Bachner, N. Efrenov, “A high-yield photolithographic technique for surface wave devices,” J. Electrochem. Soc. 118, 821–825 (1971).
[CrossRef]

Carli, B.

Casey, J. P.

Clegg, P. E.

P. E. Clegg, “The long wavelength spectrometer in ISO,” in Infrared Astronomy with ISO, Proceedings of the Les Houches Summer School, T. Encrenas, M. F. Kessler, eds., (Nova Science, New York, 1992), pp. 107–122.

De Graauw, T.

T. De Graauw, “The ISO short wavelength spectrometer,” in Infrared Astronomy with ISO, Proceedings of the Les Houches Summer School, T. Encrenas, M. F. Kessler, eds. (Nova Science, New York, 1992), pp. 125–138.

Efrenov, N.

H. Smith, F. Bachner, N. Efrenov, “A high-yield photolithographic technique for surface wave devices,” J. Electrochem. Soc. 118, 821–825 (1971).
[CrossRef]

Emery, R.

M. A. Greenhouse, H. A. Smith, J. Fischer, I. Furniss, B. Swinyard, R. Emery, “Infrared performance characteristics of low-absorption, high-reflectivity metal mesh reflectors,” to be submitted to Appl. Opt.

Fischer, J.

C. J. Taylor, H. A. Smith, J. Fischer, “Superior freestanding meshes for use as infrared Fabry–Perot elements made with a new photolithographic technique,” Rev. Sci. Instrum. 59, 1094–1097 (1988).
[CrossRef]

M. A. Greenhouse, H. A. Smith, J. Fischer, I. Furniss, B. Swinyard, R. Emery, “Infrared performance characteristics of low-absorption, high-reflectivity metal mesh reflectors,” to be submitted to Appl. Opt.

Furniss, I.

M. A. Greenhouse, H. A. Smith, J. Fischer, I. Furniss, B. Swinyard, R. Emery, “Infrared performance characteristics of low-absorption, high-reflectivity metal mesh reflectors,” to be submitted to Appl. Opt.

Genzel, L.

K. Sakai, L. Genzel, “Far infrared metal mesh filters and Fabry–Perot interferometry,” Rev. Infrared Millimeter Waves 1, 155–247 (1983).
[CrossRef]

Greenhouse, M. A.

M. A. Greenhouse, H. A. Smith, J. Fischer, I. Furniss, B. Swinyard, R. Emery, “Infrared performance characteristics of low-absorption, high-reflectivity metal mesh reflectors,” to be submitted to Appl. Opt.

Kern, W.

W. Kern, D. A. Puotinen, “Cleaning solutions based on hydrogen peroxide for use in silicon semiconductor technology,” RCA Rev. 31, 187–206 (1970).

Lewis, E. A.

Morgan, R. A.

R. A. Morgan, Plasma Etching in Semiconductor Fabrication (Elsevier, New York, 1985), Chap. 2, pp. 40–42.

Prettyjohns, K. N.

K. N. Prettyjohns, J. C. Wyant, “Three-dimensional surface metrology using a computer controlled noncontact instrument,” in Optics in Engineering Measurement, W. F. Fagan, ed., Proc. Soc. Photo-Opt. Instrum. Eng. 599, 304–308 (1986).

Puotinen, D. A.

W. Kern, D. A. Puotinen, “Cleaning solutions based on hydrogen peroxide for use in silicon semiconductor technology,” RCA Rev. 31, 187–206 (1970).

Sakai, K.

K. Sakai, L. Genzel, “Far infrared metal mesh filters and Fabry–Perot interferometry,” Rev. Infrared Millimeter Waves 1, 155–247 (1983).
[CrossRef]

Smith, H.

H. Smith, F. Bachner, N. Efrenov, “A high-yield photolithographic technique for surface wave devices,” J. Electrochem. Soc. 118, 821–825 (1971).
[CrossRef]

Smith, H. A.

C. J. Taylor, H. A. Smith, J. Fischer, “Superior freestanding meshes for use as infrared Fabry–Perot elements made with a new photolithographic technique,” Rev. Sci. Instrum. 59, 1094–1097 (1988).
[CrossRef]

M. A. Greenhouse, H. A. Smith, J. Fischer, I. Furniss, B. Swinyard, R. Emery, “Infrared performance characteristics of low-absorption, high-reflectivity metal mesh reflectors,” to be submitted to Appl. Opt.

Swinyard, B.

M. A. Greenhouse, H. A. Smith, J. Fischer, I. Furniss, B. Swinyard, R. Emery, “Infrared performance characteristics of low-absorption, high-reflectivity metal mesh reflectors,” to be submitted to Appl. Opt.

Taylor, C. J.

C. J. Taylor, H. A. Smith, J. Fischer, “Superior freestanding meshes for use as infrared Fabry–Perot elements made with a new photolithographic technique,” Rev. Sci. Instrum. 59, 1094–1097 (1988).
[CrossRef]

Vaughn, J. M.

J. M. Vaughn, The Fabry–Perot Interferometer (Hilger, Philadelphia, Pa., 1989), Chap. 10, pp. 405–422.

Wyant, J. C.

K. N. Prettyjohns, J. C. Wyant, “Three-dimensional surface metrology using a computer controlled noncontact instrument,” in Optics in Engineering Measurement, W. F. Fagan, ed., Proc. Soc. Photo-Opt. Instrum. Eng. 599, 304–308 (1986).

J. Electrochem. Soc.

H. Smith, F. Bachner, N. Efrenov, “A high-yield photolithographic technique for surface wave devices,” J. Electrochem. Soc. 118, 821–825 (1971).
[CrossRef]

J. Opt. Soc. Am.

RCA Rev.

W. Kern, D. A. Puotinen, “Cleaning solutions based on hydrogen peroxide for use in silicon semiconductor technology,” RCA Rev. 31, 187–206 (1970).

Rev. Infrared Millimeter Waves

K. Sakai, L. Genzel, “Far infrared metal mesh filters and Fabry–Perot interferometry,” Rev. Infrared Millimeter Waves 1, 155–247 (1983).
[CrossRef]

Rev. Sci. Instrum.

C. J. Taylor, H. A. Smith, J. Fischer, “Superior freestanding meshes for use as infrared Fabry–Perot elements made with a new photolithographic technique,” Rev. Sci. Instrum. 59, 1094–1097 (1988).
[CrossRef]

Other

T. De Graauw, “The ISO short wavelength spectrometer,” in Infrared Astronomy with ISO, Proceedings of the Les Houches Summer School, T. Encrenas, M. F. Kessler, eds. (Nova Science, New York, 1992), pp. 125–138.

P. E. Clegg, “The long wavelength spectrometer in ISO,” in Infrared Astronomy with ISO, Proceedings of the Les Houches Summer School, T. Encrenas, M. F. Kessler, eds., (Nova Science, New York, 1992), pp. 107–122.

M. A. Greenhouse, H. A. Smith, J. Fischer, I. Furniss, B. Swinyard, R. Emery, “Infrared performance characteristics of low-absorption, high-reflectivity metal mesh reflectors,” to be submitted to Appl. Opt.

R. A. Morgan, Plasma Etching in Semiconductor Fabrication (Elsevier, New York, 1985), Chap. 2, pp. 40–42.

K. N. Prettyjohns, J. C. Wyant, “Three-dimensional surface metrology using a computer controlled noncontact instrument,” in Optics in Engineering Measurement, W. F. Fagan, ed., Proc. Soc. Photo-Opt. Instrum. Eng. 599, 304–308 (1986).

J. M. Vaughn, The Fabry–Perot Interferometer (Hilger, Philadelphia, Pa., 1989), Chap. 10, pp. 405–422.

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Figures (5)

Fig. 1
Fig. 1

Typical freestanding mesh. The mesh is supported by an annular ring of the original silicon wafer substrate. Reflection as well as transmission is seen, which illustrates the smoothness of the mesh surface.

Fig. 2
Fig. 2

Fabrication steps: (a) A thermal oxide is grown on both sides of the wafer. (b) A chrome–gold film is deposited over the oxide on both sides of the wafer. (c) A layer of photoresist is deposited, exposed through a mask, and developed. The sidewall angle is greatly exaggerated for clarity. (d) Nickel is up-plated by the resist template to form nearly perpendicular sidewalls. (e) The resist template is removed, leaving a nickel mesh on a gold film, all on a silicon wafer. (f) The back side of the silicon wafer is thinned from the center to the edge, putting a dimple in the back side of the wafer. (g) The silicon, chrome, and oxide are etched away, leaving a full gold membrane and nickel mesh. (h) Ion milling is used to mill the gold membrane between the nickel wires, from the back side of the mesh, leaving a smooth, gold coating on the front side of the freestanding mesh.

Fig. 3
Fig. 3

Scanning electron micrographs of the front surfaces of typical freestanding meshes at (a) low magnification and (b) high magnification.

Fig. 4
Fig. 4

(a) Plot of typical mesh surface topology measured by optical-phase-measurement interferometry. The typical surface roughness of 13 nm rms is dominated by height deviations at the periphery of the mesh holes. (b) Surface roughness profile of the same mesh, measured along the center of a mesh wire. An order-of-magnitude improvement is revealed when the mesh hole edges are not included in the measurement.

Fig. 5
Fig. 5

Plot of finesse and transmission of liquid helium-cooled Fabry–Perot étalons composed of mesh reflectors produced by the process described here and the best commercially available meshes base lined for flight on the ISO.

Tables (1)

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Table 1 Mesh Uniformity and Sample-to-Sample Variation Measurements

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